In the preparation of various slurry mixtures used for different industrial applications, a volume of dry powder must be placed in a mixing apparatus where it can be combined with the proper type and amount of liquid to form the slurry. For many situations it is necessary for a relatively high volume of dry powder to be supplied to a mixing chamber containing liquid within a relatively short period of time. Often, the dry powder is a material that is toxic or in some way hazardous to a person's health if breathed in. In some situations this necessity to handle a large quantity of powder created a serious problem due to the possibility of releasing even small amounts of the powder into the surrounding atmosphere where they could be ingested by workers. For example, in the preparation of so-called body-feed slurry for industrial filter systems, it is necessary to introduce a large volume of diatomaceous earth to a mixing chamber containing a liquid coolant. Heretofore, the powdered diatomaceous earth material was typically supplied in 50 pound sacks which were manually opened and dumped into a mixer to form a slurry. Aside from the fact that such manual dumping created dust laden air that was dangerous to breathe, it was overly labor intensive and also too slow in many instances.
Accordingly, a general object of the present invention is to provide a slurry mixing apparatus with a dry powder conveying system that eliminates the possibility of releasing even small amounts of dry powder into the atmosphere; that speeds up the process of conveying the dry powder into a mixing chamber; that reduces the amount of manual labor required to supply the dry powder to a liquid and that provides a means for controlling the rate of flow of powdered material to the mixing chamber.
Yet another object of the invention is to provide a two tank mixing system for combining a dry powder with a liquid to form a slurry of a predetermined concentration with a uniform consistency.
Another object of the invention is to provide an improved mixing chamber wherein a reduced pressure can be maintained to draw in powdered material while the mixing process takes place.